• 한국막학회:학술대회논문집
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• 한국막학회 1999년도 The 7th Summer Workshop of the Membrane Society of Korea
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• pp.95-96
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• 1999

The ultrafiltration behavior of dilute colloidal solution containing Si particles has been investigated. The experiments in cross flow mode have been performed at different operating condition by using the membrane with 20 kDa cut-off. The flux decline was due to the development of membrane fouling which was a dynamic process of two distinctive stages. For the high trans-membrane pressure, the pore blocking resistance was dominant at the initial period of filtraion and was followed by the cake resistance. And for the low cross flow velocity, the membrane fouling was governed by the cake filtration model at the initial stage of filtration process. Flux jump was observed temporally during the membrane filtration of mixed feed solution.

• 상하수도학회지
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• 제22권3호
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• pp.281-288
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• 2008

Cake resistance is influenced by floc size deposited on membrane surface. Enlarging floc size can reduce cake resistance. The small particles are enlarged by coagulation and flocculation process in conventional mixing tank at membrane filtration system. Fully-grown flocs for reducing the cake resistance, however, are ruptured while passing through a pump. In light of this fact, this study aims to experimentally look at the reaggregation phenomenon of mixing system. In addition, reaggregation phenomenon of mixing system is compared with first-aggregation of in-line injection system in which coagulant is injected just before a pump. These results suggest that first-aggregation of in-line injection system is better than reaggregation of mixing system for G-value above $3100sec^{-1}$. Since G-value in pipe of actual membrane filtration system are usually larger than $3100sec^{-1}$. The performance of in-line injection system is expected to be better than the conventional mixing tank system.

• Membrane and Water Treatment
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• 제4권3호
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• pp.175-189
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• 2013

A membrane bioreactor (MBR) with sludge retention time (SRT) of 300 days was maintained for over 2 years. Polypropylene microfiltration (MF) membrane with pore size of 0.2 ${\mu}m$ was used in the MBR system. The fouling behaviors of various sludge fractions from the MBR were studied and sub-divided resistances were analyzed. It was observed that $R_{cp}$ was a dominant resistance during the filtration of activated sludge, contributing 63.0% and 59.6% to the total resistance for MBR and sequential batch reactor (SBR) respectively. On the other hand, $R_c$ played the significant role during the filtration of supernatant and solutes, varying between 54.54% and 67.18%. Compared with $R_{cp}$ and $R_c$, $R_{if}$ was negligible, and $R_m$ values remained constant at $0.20{\times}10^{12}m^{-1}$. Furthermore, resistances of all sludge fractions increased linearly with rising mixed liquor suspended solids (MLSS) concentration and growing trans-membrane pressure (TMP), while the relationship was inversed between fraction resistances and cross flow velocity (CFV). Among all fractions of activated sludge, suspended solid was the main contributor to the total resistance. A compact cake layer was clearly observed according to the field emission scanning electro microscopy (FE-SEM) images.

• 멤브레인
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• 제23권6호
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• pp.439-449
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• 2013

본 연구는 상용화된 방향족 폴리아미드 역삼투막에 diphenylamine (DPA)을 표면개질 시킴으로써 내염소성과 내오염성이 향상된 역삼투 복합막을 제조하고 최적화시키는 방법에 대해서 연구하였다. 역삼투막의 내염소성과 내오염성을 증가시키기 위해 반응성이 뛰어난 아민(amine)기를 가지고 있고 열적 화학적 안정성이 뛰어난 페닐기 2개가 있는 DPA를 사용하였고, 개질 온도와 시약 농도를 변화시켜가며 개질 조건을 최적화시켰다. XPS, AFM 그리고 contact angle을 이용하여 역삼투막의 표면 개질을 통한 표면 특성 변화를 확인하였으며 역삼투막의 투과성능 평가 결과 역삼투막의 내염소성과 내오염성이 향상된 역삼투 분리막을 제조하였다.

• 한국물환경학회지
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• 제22권1호
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• pp.17-22
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• 2006

This study is about backwash condition and membrane fouling at continuous coagulation/ultrafiltration process in water treatment. The capacity of pilot plant was $0.06m^3/d$. The result of the test, Backwash cycle time and duration time had a significant effect on the efficiency of system and backwash. Backwash duration time was determined to be fixed in 30 seconds for the system with more than 95% recovery rate, It needed 30 minute backwash frequency. During the continuous operation, membrane fouling was analyzed by determining the filtration resistance ($R_i$) and cake layer resistance ($R_c$). At the initial stage, filtration resistance highly influenced the fouling behavior. But after 1.5 hours, cake layer resistance became more important than filtration resistant.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2009년도 추계 학술논문 발표대회
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• pp.141-148
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• 2009

The purpose of this paper is to propose a standard test methods of resistance to root penetration for waterproofing and rootproofing membrane using green roof system. Green roof system is considered to be an important subject in construction industry for green growth project. At the same time, we have to consider the counterplan for protection the damage of waterproofing layer and concrete substrate from the penetration of plant root. But many kinds of materials for protection from root penetration are using in construction field. But the performance of those materials is not clear, and there is not test methods for the evaluation of performance. So in this paper, based on the research results of 4 institutes during four years and foreign cases, we made a standard test methods of resistance to root penetration for waterproofing and rootproofing membrane using green roof system. This test method deals with about environmental condition of laboratory, experimental facilities, kinds of plant, specimen of test, management methods, evaluation duration and documents, etc.

• Computers and Concrete
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• 제31권6호
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• pp.469-484
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• 2023

The response mechanism of simply supported two-way reinforced concrete (RC) slabs under fire was numerically studied from the view of stress redistribution using the finite element software ABAQUS. Results show that: (1) Simply supported two-way RC slabs undergo intense stress redistribution, and their responses show four stages, namely elastic, elastic-plastic, plastic and tensile membrane stages. There is no cracking in the fire area of the slabs until the tensile membrane stage. (2) The inverted arch effect and tensile membrane effect improve the fire resistance of the two-way slabs. When the deflection is L/20, the slab is in an inverted arch effect state, and the slab still has a good deflection reserve. The deformation rate of the slab in the tensile membrane stage is smaller than that in the elastic-plastic and plastic stages. (3) Fire resistance of square slabs is better than that of rectangular slabs. Besides, increasing the reinforcement ratio or slab thickness improves the fire resistance of the slabs. However, an increase of cover thickness has little effect on the fire resistance of two-way slabs. (4) Compared with one-way slabs, the time for two-way slabs to enter the plastic and tensile cracking stage is postponed, and the deformation rate in the plastic and tensile cracking stage is also slowed down. (5) The simply supported two-way RC slabs can satisfy with the requirements of a class I fire resistance rating of 90 min without additional fire protection.

• 멤브레인
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• 제30권2호
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• pp.138-148
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• 2020

본 연구는 (주)퓨어엔비텍에서 제조한 multi-bore 형태의 중공사 막을 이용하여 오염된 원수의 투과 후 오염된 막의 재사용을 위해 화학적 세정효율에 대해 파악하고자 하였으며 이를 위해 제조된 중공사 막의 재료는 내화학성이 좋은 PSf(polysulfone) 소재를 사용하였다. 실험은 소혈청 알부민(BSA)을 이용한 내오염성 평가 및 염기성 용액인 차아염소산나트륨(NaOCl), 산성 용액인 구연산(citric acid)을 이용해 장기 함침하여 내화학성 평가를 진행하였다. 시간에 따른 수투과도와 인장강도를 측정하여 분리막의 기계적 강도와 성능의 감소에 대한 결과를 관찰하였다. 이후 소혈청 알부민으로 오염된 막의 화학적 용액에 따른 역세척 후 회복효율을 파악하였다. PSf 중공사 막은 뛰어난 내화학성을 가졌으며 화학적세척결과 차아염소산나트륨의 효율이 높음을 확인하였다.

• 한국물환경학회지
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• 제21권4호
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• pp.337-346
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• 2005

An MSBR using a membrane for not only filtration but also aeration (MA-MSBR) was designed to reduce membrane fouling and to enhance water quality, and compared with an MSBR using a membrane for only filtration (BA-MSBR). COD removal efficiency of the MA-MSBR was similar to that of the BA-MSBR, but membrane performance of the MA-MSBR was better than that of the BA-MSBR. The MA-MSBR had more small particles in mixed liquor, so the specific cake resistance of flocs in the MA-MSBR was higher than that in the BA-MSBR. However, in the aerobic reaction step of the MA-MSBR, air went through membrane pores and out of the membrane surface, so cake layers on the membrane surface and a portion of organics adsorbed on membrane pores could be removed periodically. Therefore, cake resistance, $R_c$, and fouling resistance by adsorption and blocking, $R_f$, for the MA-MSBR increased more slowly than those for the BA-MSBR. Additionally, in order to compare the energy efficiency for two MSBRs, oxygen transfer efficiency and power to supply air into the reactor by a membrane module and a bubble stone diffuser were measured using deionized water. From these measurements, the transferred oxygen amount per unit energy was calculated, resulting that of MA-MSBR was slightly higher than that of BA-MSBR.

• Korean Chemical Engineering Research
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• 제58권2호
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• pp.171-175
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• 2020

고분자전해질 연료전지(PEMFC)에서 지지체에 의해 내구성을 향상시킨 강화막(Reinforced Membrane)의 개발이 국내에서 활발히 진행되고 있다. 본 연구에서는 4 종류의 강화막의 초기 성능 및 특성을 비교하였다. 고분자막의 C-F사슬의 양이 더 많은 강화막이 C-F사슬의 소수성 때문에 물 확산계수가 더 작음을 보였다. 고분자막 두께가 두꺼울수록 수소투과도가 감소하고 OCV가 증가함을 확인하였다. Short 저항이 1.5 Ωcm² 이하인 막은 OCV가 0.9 V이하이고 성능도 최저여서 Short 저항이 3.0 Ωcm² 이상이어야 함을 보였다. 현재 기준이 되는 국외 막과 비교했을 때 비슷한 국내 막도 있어서 PEMFC 고분자막의 국산화 가능성을 확인할 수 있었다.